Production of cinematograph film



Oct. 10, 1933. '0. E. THORNTON PRODUCTION OF CII'EMATOGRAPH FILM Tig.

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lOOOOOOUODOUODO/ Oct. 10, 1933. J. E. THORNTON 1,930,291.

PRODUCTION OF CINEMATOGRAPH FILM Filed DeC. 31, 1931 2 Sheets-Sheet 2mwn///l//a/d IIIIllllllllllllllllllllllllllllll n /raas @ver Figli.

Patented ocr. 1o, 1933 y UNITEDl STATE-s PMIrNT` OFFICE ApplicationDecember 31, 1931 Serial No. 584,194

1 Claim.

This invention relates to the production of cinematograph or othercontinuous film-positives of two (or more) colors by means of a centralsupport of transparent film-material suitably 5 prepared with twoadhesive substratums andA two (or more) photographically producedcomponent images which have been printed from the front then applied tosuch substratums upon opposite sides of the transparent support, byfirst preparing the images each upon a temporary support of porouspaper, and then transferring and cementing the two images to theadhesive substratums by pressure-contact assisted by moisture and withtheir printed faces in contact with the substratums, then drying outthemoisture, and subsequently developing both images from the back oropposite faces simultaneously and removing and discarding the twotemporary supports of paper, and is a modification of my prior Patent1,873,674, dated August 23, 1932.

The objects of the invention are two fold, viz:- (1) To enable aV filmto be produced with only one piece of transparent support or lmmaterial, and with two relief images which are exposed from the back(and developed from the front) whilst on a temporary. support of porouspaper from which they are subsequently transferred on the one centralpermanent transparent support back-to-back; and

(2) To provide a means or method by which absolutely accurate registerof the two component images forming one picture can be ensured by aprocess of simultaneous registration and simultaneous transfer andcementing of the two images tothe one central transparent support.

, State of the art Many investigators have endeavored to produce acontinuous strip of cinematograph filmr 4Q with a single support oftransparent film and two differently colored colloid relief images uponopposite sides of the support in accurate register with each other. Onemethod for producing such an article hitherto has been by using two thinsupports, each sensitized upon one side, exposing each in printingthrough the back of its transparent support, developing the images fromthe unprinted front side of the film, and cementing the two supportstogether back-to-back either before or after developing to form a singlefilm. Both strips were perforated before printing, and the perforationsserved as means of registration when printing and when cementing. Theresult l was technically satisfactory, but objections were made againstthis method upon the ground that two thin supports cost more to producethan one `support of equal thickness to the two combined.

registration this proved useless owing to unavoidable variation inlength relatively to the different strips, owing to expansion andcontraction during the Wet processes of transfer, and

therefore the original perforations made in all three bands were at thisstage not the same pitch in the transparent final support and thetemporary. supports. Therefore the original per- 7 forations made in thetransparent support were useless as traction perforations because theydid not place and locate the pictures correctly during projection.

The present invention is designed to overcome both objections, which itaccomplishes by the following combination of methods and ofconstruction:-

(A) The images are printed by exposure to light through negatives on tosensitized colloid carried upon the front face of paper strips ortemporary supports, both of which have identical perforations andtherefore accurately register with each other when laid face-to-face.

(B) The printed images upon the two temporary supports are thenaccurately registered opposite each other, exposed-face towardsexposedface, by and upon a pair of registration sprockets, the .teeth ofwhich exactly fit the perforations of the printed strips.

l(C) The printed images are then transferred to the two preparedadhesive surfaces of the transparent film which forms the permanentsupport and at this stage has no perforations transfer being effected bypressure when all three bands are clamped together.

(D) The printed images are then developed into relief images upon thepermanent support of transparent film, the temporary paper supportsbeing discarded in the process.

(E) Finally a series of traction perforations are made in thetransparent support and the two-color positive is then complete.

The methods and means .of carrying out the invention'will now bedescribed in fuller detail.

In carrying out the invention a double-width strip of porous paper isprovided on its surface with a layer of suitable colloid such as softgelatine, which is sensitized either with silver salts in the usual wayas an emulsion or with bichromate salts applied by absorption.

Suitable coloring matter, preferably mordanted dye, is incorporated withthe colloid during manufacture of the sensitized paper, in such mannerthat one half the width contains one color and the other half widthcontains the other color.

This double-width paper positive strip is printed with twoimages from adouble-width, negative strip in known manner, either by contact or byprojection.

The margins are given a separate or supplementary exposure in order toproduce insoluble solid relief margins, as in my Patents 1,674,810 and1,672,352, instead of the usual transparent and bare margins of otherprocesses.

After printing, the strip is longitudinally divided into twosingle-width strips, and these are next laid upon the non-perforatedsinglewidth transparent film strip with one of the printed faces incontact with one of the substratums and the other printed face incontact with the other substratum. To ensure satisfactory contact thesurfaces are dampened, the simplest way of producing `iust the rightcondition being to pass the strip of transparent support through a waterbath (which may contain a very small proportion of acetic acid) andpress the dry faces of the printed strips into contact with the dampadhesive substratums. After a suitable period of contact theadhesion ofthe two surfaces will be sufficiently firm and the triple band is thenpassed through a drying chamber until sufficiently dry.

When permanent adhesion of the printed faces of each transferred film toeach substratum has been firmly established, the complete strip issubmitted to the usual developing and other processes of treating toproduce relief images. These operations will vary Iaccording to the typeof sensitized surface used.

For example, if the colloid has been sensitized with bichromate,development is effected by hot water alone which is applied to the backof the printed image through the porous paper, the hot water dissolvingall soft colloid and allowing the paper to come away from the film andbe discarded entirely, and leaving behind firmly attached to thetransparent support a series of relief images of insoluble colloid.

`If however, the sensitive colloid consists of a gelatine-silveremulsion it will, after printing, require the additional treatment ofdeveloping the silver image, then tanning the gelatine of the silverimage in order to render it insoluble, and then total removal of thesilver by means of the usual solvents; and when all these operationshave been completed the film is treated with hot water to dissolve andremove the soft gelatine and leave behind relief images of insolublecolloid, as in the previous example.

The coloring matter is preferably incorporated with the colloid in theform of transparent mordanted dyes at the time of manufacturing thesensitive paper, and therefore when the images are converted intoreliefs theyv will be readycolored reliefs. I

But the process can also be used with noncolored sensitive paper. inwhich 'case the reliefimages, when the developing and -treatingprocesses have been completed, will be colorless and transparent. Theyare nextdyed to the right colors by application of suitable dyes in adyeing machine fed by ductor rollers, and are afterwards mordanted topermanently fix the colors.

The feature of the invention which renders the successful carrying outof the process possible is the means of registration.

The invention will be described with reference to the accompanyingdrawings:-

Fig. l is a diagrammatic view of the apparatus for carrying out theinvention.

Fig. 2 is a transverse section through the temporary supports and filmstrip.

Fig. 3 is a transverse section through the film positive.

Fig. 4 is a perspective view of non-perforated transparent celluloidfilm-strip showing an adhesive substratum upon each side.

Fig. 5 is a plan of porous paper strip and sensitized colloid layer andimages thereon, after development.

Fig. 6 is a plan of the other similar strip (complementary lto thefirs't strip) showing its images reversed with respect to those on thestrip Fig. 5.

Fig. 7 is a very much magnified cross section showing the two papertemporary strips after development with their images of insolublehardened and soluble non-hardened colored colloid represented by thedarker shading, each image being of a different color, and withregistration perforations in the extended margins of the paper strips,these being the first or temporary perforations which are used only forregistration purposes in the printing and cementing operations. Thesketch shows the two printed strips and the transparent celluloid stripin their relative positions before the printed images are cemented tothe adhesive substratums of the transparent celluloid strip by pressureand moisture combined.

Fig. 8 is a very much magnified cross section showing the three parts ofthe lm after development and after cementing, but before its finaldevelopment into relief, consisting of five layers all united togetheras one solid strip, and showing the registration perforations in the twopaper temporary strips. 4

Fig. 9 shows the paper strips being removed from the nlm as it emergesfrom the hot water tank in which the developed images are converted intorelief images attached upon both sides of the film support; theunfinished film of five layers having all been perforated together andtherefore the two paper strips have two sets of perforations each, onefor registration and the other for traction purposes.

Fig. l0 is an enlarged longitudinal section of the five layer unfinishedfilm.

Fig. 11 shows a very much magnified cross section of the finished2-color film-positive, comprising a central strip of transparent filmhaving a series of traction perforations and a colloid relief image inblue-green permanently attached to one side, and another colloid reliefimage in orange-red permanently attached to the other side of thetransparent celluloid support.

Fig. l2 is a very much magnified longitudinal section of a film havingdeveloped images on only one side before conversion into reliefs.

The transfer of the images is effected in the following way:-

The two images are first printed on a strip of double-width which isdivided into two strips after printing and developing the images andbefore squeegeeing them to the transparent support and before conversioninto reliefs. The Figs. 5 and 6 show the two strips after division widerthan the finished film.

The two printed colloid images, whilst still attached to their papersupports, are first squeegeedinto contact with the twosticky adhesivefaces of the central transparent film. They are' a drying chamber, fromwhich it emerges dry'.

with all the layers firmly stuck together, the necessary time requiredto ensure perfect and permanent adhesion being provided by the length oftravel through the drying chamber. This complete band, comprising fivelayers, is shown in magnified form in Figs. 9 and 10.

The solid band then passes 'through a perforating apparatus where thenon-perforated central film y is perforated, the punches passing throughthe whole solid band, comprising all the aforesaid layers, including onefilm, two substratums, two printed colloid layers, and two papersupports. l

In a modification the film may be perforated before being sandwichedbetween the two paper strips and the two paper strips will then onlyhave one set of registration perforations and the celluloid strip hasone set of perforations for traction purposes.

The solid band then passes into a hot water tank. The hot water passesthrough the porous paper and dissolves some of the gelatine, so that thetwo papers no longer stick and'can therefore part company from the film,leaving the two printed images on the films instead of on the papers.

A suitable machine for registering, adhering and developing the stripsand also for perforating is described in application Serial No. 366,743filed May 28, 1929.

`In previously known and used methods of transferring two series oftransfer images from two paper strips on to transparent film, it hasbeen usual toA transfer them separatelyone after the other, andgenerally one over the other. In the period between transferring thefirst and the second series of images one series wouldalter in lengthcompared with the other, owing to expansion or contraction of either thepaper strip or the transparent strip, or both, with .the result that thetwo component images never registered accurately one over the other, andtherefore when the picture was magnified upon the screen thisdifference, though slight in the prints, was greatly magnified, thusspoilingthe result.

In the present invention this serious defect is entirely eliminated, andaccurate register en.- sured, by the hereinbefore described system ofprinting both sets of images simultaneously on the one double-widthstrip, and registering and transferring them simultaneously by two setsof registration devices which interlock as one common device only, anddeveloping them simultaneously. l

'I'hese registering-devices may comprise a pair ot opposite placedwheels or drums having accurately cut sprocket teeth projecting from thesurface of each drum, the two paper strips having each'a series ofaccurately punched perforations which are accurately spaced to the samepitch as the sprocket teeth.

To ensure the best results the teeth of one sprocket fit into holes inthe other sprocket alternately, that is to say half the positions oneach vsprocket comprise projecting teeth and the other half positionscomprise holes placed in the alternate positions between them. Thereforeone paper strip is always properly registered upon its own set of teethand the other strip is likewise always properly registered upon its ownset of teeth.

This pair of sprockets always` brings the pair of paper strips to theimpression point where allthree strips are squeezed together. In effectthey form a pair of smooth-faced drums or rollers between which theimages to be transferred and the transparent support are gripped, thepaper strips passing over or around one half of each of the said drums.The drums may, if desired, be rubber covered to provide slightlyyielding pads. Y,

' The above described method of obtaining accu-n rate register requiresthat the pair. of paper strips" should be of greater width than the filmand that they should have the registration perforations in the marginsoutside the width of the fil The same accurate registration can alg@obtained with paper strips of the same widths the film strip and withthe perforations in the usual margins vcommonly allowed in the filmprinting by employing two sprocket wheels the teeth of which do notthemselves interlock but which are instead intergeared and driven from acommon shaft through worm or bevel gearing. These sprocket wheels arearranged above the impression point, the latter being obtained by thefirst pair of a series of pairs of smooth rollers. Thus the contact ofthe two paper strips with the film strip does not commence until afterthe paper strips have passed the registering sprocket wheels instead ofat the interlocking sprocket wheels in the earlier described method ofobtaining accurate registration.

In both methods two paper strips are independently registered byindependent sprockets. but in both methods these sprockets are under onecommon control either by being interlocked or intergeared, and the blankfilm is drawn or fed forward by the usual means, and is accuratelyguided upon each side to the impression point so that it is accuratelyplaced in the right track at the period of impression. 12

The drawings (Fig. 1) show the process in principle but the completemechanisms and modiflcations there of for carrying out the transfer areshown in detail in the machine described in my L specification SerialNo. 564,360 filed September 22nd, 1931.

The transferring machine comprises a suitable reels, and with suitablefeed sprockets or drums for supporting and feeding the: two paper strips135 and the transparent strip 'and bringing them to the pressure rolls,after which the combined triple strip passes to developing and treatingapparatus of any suitable known kind, but preferably to a machine suchas described in my prior Patent No. '1,736,557 dated November 19, 1929.

The colors used in producing a film according to the invention arevaried as required. For a two-color natural photograph one color will be145. orange-red and the other blue-green. For a stereoscopic picture ofthe non-registering type one image will be red and the other green.

Monochrome pictures comprising images on one side only of the filmsupport may be transferred and treated in the same way, as shown in Fig.12.

If four-color films are required the operations are repeated bytransferring a second set of image-components on to and superimposedupon the rst set, the colors in that case being preferably red, green,violet and orange.

In my Patents Nos. 1,250,713 and 1,173,898 and 1,173,899 I havedescribed a process for manufacturing a color lm comprising a centraltransparentA support with a differently-colored image upon each side,and which is produced by sensitizing the transparent support itself uponboth sides and interposing a light-obstructing layer between the supportand sensitized layers, and each sensitized layer is printed by exposurefrom its face side whilst forming an integral part of the lrn.

In the present invention the central transparent support is plain andnot sensitized, there are no light-obstructing layers, the sensitivelayers are carried before printing upon separate temporary papersupports, they are each printed from the face side of the sensitizedlayer, and after printing the sensitized layers are cemented by their,printed faces to the central transparent support so that the printedsides are inwards,

and are finally developed into reliefs from the back of each printthrough the porous paper;

therefore the former backs of each print become the outside fronts ofthe completed nlm (the images having been 'inverted in the process).

The negatives used in printing have one image of the pair reversed inrelation to the other image.

What I claim as my invention and desire to protect by Letters Patent isA method for the production of cinematograph 111m positives from partialimages carried on separate porous paper supports comprising registeringthe paper supports one on each side of a nonperforated llm base,simultaneously transferring the images from the paper supports on toeach side of the lm base by pressure contact, passing the combined bandfirstly through a drying chamber, secondly through a perforating machinewhich punches traction perfor-ations therein and thirdly through a hotwater bath which loosens the porous paper from the film strip and nallystripping the porous paper therefrom to leave a film strip having reliefimages on each side in accurate register.

J OHN EDWARD THORNTON.

